Micro Electro-Mechanical System (MEMS) inertial sensors, including accelerometers, gyroscopes and magnetometers, are generally well-known and commercially available from Honeywell International, Incorporated, the assignee of the present patent application. MEMS inertial sensors typically have a single input axis. To achieve an effective 3-axis inertial system three individual MEMS inertial sensors are arranged in an orthogonal manner. For example, three individual inertial sensors may be mounted directly on the host structure to be monitored. Alternatively, the individual MEMS inertial sensors are combined in 3-dimensional structural package for sensing inputs in three orthogonal directions, as disclosed by the inventor of the present invention in U.S. Pat. No. 6,918,297, Miniature 3-Dimensional Package for MEMS Sensors, which is assigned to the assignee of the present application and is incorporated herein by reference.
However, orthogonal arrangements of MEMS inertial sensor typically require at least one sensor, and sometimes two, to be arranged perpendicular to an easily available mounting plane. Also, most inertial sensors require packaging of a type that maintains sealing of their internal environment as such devices typically must operate in either a vacuum or stable atmosphere such as dry nitrogen. Typical MEMS sensor packaging is designed around planar integrated circuitry packages such as Leadless Chip Carriers, Ball-Grid-Arrays, or Flip-Chip or Chip-Scale Level packages. These IC packages present the MEMS sensor sense axis in only one orientation. Assembly of a functional 3-axis inertial reference system (IRS) requires at least one, and sometimes two, of these IC packages to be placed perpendicular to the surface of a functional electronic printed circuit board. Such mounting constraints require increased IRS size to accommodate the MEMS IC package mounting perpendicular to the PCB. Additional issues that arise include the need for routing signals from the MEMS IC package to the PCB, assembly cost increases associated with the non-traditional orientation of the IC package, and compromised reliability due to straining of the MEMS IC package attachment through operational environments.